// SPDX-License-Identifier: Unlicense OR MIT

package main_test

import (
	"flag"
	"image"
	"testing"
)

var headless = flag.Bool("headless", true, "run end-to-end tests in headless mode")

// TestDriver is implemented by each of the platforms we can run end-to-end
// tests on. None of its methods return any errors, as the errors are directly
// reported to testing.T via methods like Fatal.
type TestDriver interface {
	// Start provides the test driver with a testing.T, as well as the path
	// to the Gio app to use for the test. The app will be run with the
	// given width and height. When the function returns, the gio app must
	// be ready to use on the platform.
	//
	// The returned cleanup funcs must be run in reverse order, to mimic
	// deferred funcs.
	// TODO(mvdan): replace with testing.T.Cleanup once Go 1.14 is out.
	Start(t *testing.T, path string, width, height int) (cleanups []func())

	// Screenshot takes a screenshot of the Gio app on the platform.
	Screenshot() image.Image
}

func runEndToEndTest(t *testing.T, driver TestDriver) {
	width, height := 800, 600
	cleanups := driver.Start(t, "testdata/red.go", width, height)

	// We expect to receive a 800x600px screenshot that's filled with
	// 0xdeadbeef as the color.
	img := driver.Screenshot()
	size := img.Bounds().Size()
	if size.X != width || size.Y != height {
		t.Fatalf("expected dimensions to be %d*%d, got %d*%d",
			width, height, size.X, size.Y)
	}
	wantColor(t, img, 5, 5, 0xdede, 0xadad, 0xbebe)
	wantColor(t, img, width-5, height-5, 0xdede, 0xadad, 0xbebe)

	// Run the cleanup funcs from last to first, as if they were defers.
	for i := len(cleanups) - 1; i >= 0; i-- {
		cleanups[i]()
	}
}

func wantColor(t *testing.T, img image.Image, x, y int, r, g, b uint32) {
	color := img.At(x, y)
	r_, g_, b_, _ := color.RGBA()
	if r_ != r || g_ != g || b_ != b {
		t.Errorf("got 0x%04x%04x%04x at (%d,%d), want 0x%04x%04x%04x",
			r_, g_, b_, x, y, r, g, b)
	}
}